Uplink transmission power configuration method and apparatus for mobile communication system

ABSTRACT

A method and an apparatus for configuring uplink transmission power and apparatus in a mobile communication system supporting downlink and uplink carrier aggregation are provided. The method includes determining a per-terminal maximum transmission power and per-serving cell maximum transmission powers based on ΔT C,c  as a value for allowing an adjustment of additional transmission power for multiple serving cells, Maximum Power Reduction c  (MPR c ) as a value determined according to an amount of transmission resources allocated to the terminal, and Additive-MPR c  (A-MPR c ) as a value determined according to local characteristics and frequency band characteristics, determining per-serving cell uplink transmission powers by restricting required transmission powers for respective serving cells to the corresponding per-serving cell maximum transmission powers, comparing a sum of the per-serving cell uplink transmission powers with the per-terminal maximum transmission power, and adjusting the per-serving cell uplink transmission powers according to comparison result.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional patent application No. 61/431,635 filed on Jan. 11, 2011 inthe U.S. Patent and Trademark Office, and under 35 U.S.C. §119(a) of aKorean patent application filed on Sep. 27, 2011 in the KoreanIntellectual Property Office and assigned Serial No. 10-2011-0097409 anda Korean patent application filed on Dec. 26, 2011 in the KoreanIntellectual Property Office and assigned Serial No. 10-2011-0142069,the entire disclosure of each of which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an uplink transmission powerconfiguration method and apparatus of a mobile communication system.More particularly, the present invention relates to a method andapparatus for configuring uplink transmission power in a mobilecommunication system supporting downlink and uplink carrier aggregation.

2. Description of the Related Art

Mobile communication systems were originally developed to providesubscribers with voice communication services on the move. With therapid advancement of various technologies, the mobile communicationsystems have evolved to support high speed data communication servicesas well as the voice communication services.

Recently, a next generation mobile communication system of the 3rdGeneration Partnership Project (3GPP), referred to as a Long TermEvolution (LTE) system, is under development. The LTE system is atechnology for realizing high-speed packet-based communication at about100 Mbps. Recently, an LTE-Advanced (LTE-A) system is actively discussedas an evolution of the LTE system. The LTE-A system employs newtechniques to increase the data rate. Hereinafter, both the legacy LTEsystem and LTE-A system are referred to as the LTE system. The LTEsystem employs carrier aggregation as one of the significanttechnologies to meet broader bandwidth requirements. The carrieraggregation is a technology for a User Equipment (UE) totransmit/receive data over multiple carriers. More specifically, the UEtransmits/receives data in cells using carriers that are aggregated (forcells under the control of the same evolved Node B (eNB)). This meansthat the UE transmits/receives data in multiple cells.

In a mobile communication system of the related art, the single carrieruplink transmission power of a UE is calculated based on the scheduledresource amount, coding rate, and channel condition. The UE determinesthe final uplink transmission power by limiting the calculatedtransmission power to a predetermined maximum transmission power.

However, the uplink transmission power configuration technique of therelated, which is designed for single carrier uplink transmission, isnot appropriate for the multicarrier uplink transmission. Therefore,there is a need for a method for configuring uplink transmission powerper uplink carrier in the system supporting uplink carrier aggregationthat is capable maintaining a UE's required transmission power as muchas possible while minimizing interference between frequency bands orcells.

SUMMARY OF THE INVENTION

Aspects of the present invention are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention is to provide a method and apparatus for determiningper-carrier uplink transmission power of a User Equipment (UE) in amobile communication system supporting carrier aggregation.

Another aspect of the present invention is to provide a method andapparatus for determining per-carrier uplink transmission power that iscapable of securing the transmission power required for multicarrieruplink transmission while minimizing inter-carrier interference.

In accordance with an aspect of the present invention, a method fordetermining uplink transmission power of a terminal is provided. Themethod includes determining a per-terminal maximum transmission powerand per-serving cell maximum transmission powers based on ΔT_(C,c) as avalue for allowing an adjustment of additional transmission power formultiple serving cells, Maximum Power Reduction_(c) (MPR_(c)) as a valuedetermined according to an amount of transmission resources allocated tothe terminal, and Additive-MPR_(c) (A-MPR_(c)) as a value determinedaccording to local characteristics and frequency band characteristics,determining per-serving cell uplink transmission powers by restrictingrequired transmission powers for respective serving cells to thecorresponding per-serving cell maximum transmission powers, comparing asum of the per-serving cell uplink transmission powers with theper-terminal maximum transmission power, and adjusting the per-servingcell uplink transmission powers according to comparison result.

Preferably, the per-terminal maximum transmission power is determined inconsideration of at least one of P(Power management)-MPR applied forfulfilling a Specific Absorption Rate (SAR) requirement, the ΔT_(C,c),the MPR_(c), and the A-MPR_(c).

In accordance with another aspect of the present invention, a method fordetermining uplink transmission power of a terminal is provided. Themethod includes determining a per-terminal maximum transmission powerwith per-serving cell maximum transmission powers based on P-MPR appliedfor fulfilling a SAR requirement, ΔT_(C,c) as a value for allowing anadjustment of additional transmission power for multiple serving cells,MPR_(c) as a value determined according to an amount of transmissionresources allocated to the terminal, and A-MPR_(c) as a value determinedaccording to local characteristics and frequency band characteristics,determining per-serving cell uplink transmission powers by restrictingrequired transmission powers for respective serving cells to thecorresponding per-serving cell maximum transmission powers, comparing asum of the per-serving cell uplink transmission powers with theper-terminal maximum transmission power, and adjusting the per-servingcell uplink transmission powers according to comparison result.

Preferably, the per-serving cell maximum transmission powers aredetermined using at least one of the ΔT_(C,c), the MPR_(c), and theA-MPR_(c).

In accordance with still another aspect of the present invention, anapparatus for determining uplink transmission power is provided. Theapparatus includes a transceiver which transmits and receives data andcontrol signals in multiple serving cells, and a controller whichdetermines, when an uplink transmission message is received by thetransceiver, a per-terminal maximum transmission power and per-servingcell maximum transmission powers using parameters related to frequenciesor frequency bands of cells having uplink transmission, which determinesper-serving cell uplink transmission powers by comparing requiredtransmission powers for respective serving cells with correspondingper-serving cell maximum transmission powers, which determines finalper-serving cell uplink transmission powers by comparing a sum of theper-serving cell uplink transmission powers with the per-terminalmaximum transmission power, and which controls the transceiver toperform uplink transmission according to the final per-serving celluplink transmission powers.

Preferably, the per-serving cell maximum transmission powers aredetermined based on ΔT_(C,c) as a value for allowing an adjustment ofadditional transmission power for multiple serving cells, MPR_(c) as avalue determined according to an amount of transmission resourcesallocated to the terminal, and A-MPR_(c) as a value determined accordingto local characteristics and frequency band characteristics.

Preferably, the per-terminal maximum transmission power is determined inconsideration of P-MPR applied for fulfilling a SAR requirement,ΔT_(C,c) as a value for allowing adjustment of additional transmissionpower for multiple serving cells, MPR_(c) as a value determinedaccording to an amount of transmission resources allocated to theterminal, and A-MPR_(c) as a value determined according to localcharacteristics and frequency band characteristics.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a diagram illustrating an architecture of a mobilecommunication system according to an exemplary embodiment of the presentinvention;

FIG. 2 is a diagram illustrating a protocol stack of a mobilecommunication system according to an exemplary embodiment of the presentinvention;

FIG. 3 is a diagram illustrating an exemplary situation of carrieraggregation in a mobile communication system according to an exemplaryembodiment of the present invention;

FIG. 4 is a diagram illustrating a principle of determining uplinktransmission power in multicarrier transmission of a User Equipment (UE)according to a first exemplary embodiment of the present invention;

FIG. 5 is a signaling diagram illustrating a method for determininguplink transmission power of a UE according to the first exemplaryembodiment of the present invention;

FIG. 6 is a flowchart illustrating a method for determining uplinktransmission power of a UE according to the first exemplary embodimentof the present invention;

FIG. 7 is a block diagram illustrating a configuration of a UE accordingto the first exemplary embodiment of the present invention;

FIG. 8 is a diagram illustrating a structure of a Power Headroom Report(PHR) for use in an uplink transmission power configuration methodaccording to an exemplary embodiment of the present invention;

FIG. 9 is a diagram illustrating a structure of a PHR for use in anuplink transmission power configuration method according to a secondexemplary embodiment of the present invention; and

FIG. 10 is a flowchart illustrating a method for transmitting a PHRaccording to the second exemplary embodiment of the present invention.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention is provided for illustration purpose only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Exemplary embodiments of the present invention relate to a method forconfiguring uplink transmission power per uplink carrier in a mobilecommunication system supporting carrier aggregation.

FIG. 1 is a diagram illustrating an architecture of a mobilecommunication system according to an exemplary embodiment of the presentinvention.

Referring to FIG. 1, the radio access network of the mobilecommunication system includes evolved Node Bs (eNBs) 105, 110, 115, and120, a Mobility Management Entity (MME) 125, and a Serving-Gateway(S-GW) 130. User Equipment (UE) 135 connects to an external network viaeNBs 105, 110, 115, and 120 and the S-GW 130.

The eNBs 105, 110, 115, and 120 correspond to legacy node Bs of aUniversal Mobile Communications System (UMTS). The eNBs 105, 110, 115,and 120 allow the UE 135 to establish a radio link and are responsiblefor complicated functions as compared to the legacy node B. In a LongTerm Evolution (LTE) system, all the user traffic including real timeservices such as Voice over Internet Protocol (VoIP) are providedthrough a shared channel and thus there is a need for a device which islocated in the eNB to schedule data based on the state information suchas at least one of UE buffer conditions, power headroom state, channelstate, etc. Typically, one eNB controls a plurality of cells. In orderto secure the data rate of up to 100 Mbps, the LTE system adoptsOrthogonal Frequency Division Multiplexing (OFDM) as a radio accesstechnology. Also, the LTE system adopts Adaptive Modulation and Coding(AMC) to determine the modulation scheme and channel coding rate inadaptation to the channel condition of the UE.

The S-GW 130 is an entity that provides data bearers so as to establishand release data bearers under the control of the MME 125. The MME 125is responsible for various control functions and is connected to theeNBs 105, 110, 115, and 120.

FIG. 2 is a diagram illustrating a protocol stack of a mobilecommunication system according to an exemplary embodiment of the presentinvention.

Referring to FIG. 2, the protocol stack of the LTE system for use by aUE and an eNB includes a Packet Data Convergence Protocol (PDCP) layer205 and 240, a Radio Link Control (RLC) layer 210 and 235, a MediumAccess Control (MAC) layer 215 and 230, and a Physical (PHY) layer 220and 225. The PDCP layer 205 and 240 is responsible for Internet Protocol(IP) header compression/decompression. The RLC layer 210 and 235 isresponsible for segmenting the PDCP Protocol Data Unit (PDU) intosegments of an appropriate size for an Automatic Repeat Request (ARQ)operation. The MAC layer 215 and 230 is responsible for establishingconnection to a plurality of RLC entities so as to multiplex RLC PDUsinto MAC PDUs and demultiplex the MAC PDUs into RLC PDUs. The PHY layer220 and 225 performs channel coding on the MAC PDU and modulates the MACPDU into OFDM symbols to transmit over a radio channel or performsdemodulating and channel-decoding on received OFDM symbols and deliversthe decoded data to a higher layer.

FIG. 3 is a diagram illustrating an exemplary situation of carrieraggregation in a mobile communication system according to an exemplaryembodiment of the present invention.

Referring to FIG. 3, typically an eNB can use multiple carrierstransmitted and received in different frequency bands. For example, theeNB 305 can be configured to use the carrier 315 with center frequencyf1 and the carrier 310 with center frequency f3. If carrier aggregationis not supported, the UE 330 transmits/receives data using one of thecarriers 310 and 315. However, the UE 330 having the carrier aggregationcapability can transmit/receive data using both of the carriers 310 and315. The eNB can increase the amount of the resources to be allocated tothe UE having the carrier aggregation capability in adaptation to thechannel condition of the UE so as to improve the data rate of the UE.

In a case where a cell is configured with one downlink carrier and oneuplink carrier as a concept of the related art, the carrier aggregationcan be understood as if the UE communicates data via multiple cells.With the use of carrier aggregation, the maximum data rate increases inproportion to the number of aggregated carriers.

In the following description, the phrase “the UE receives data through acertain downlink carrier or transmits data through a certain uplinkcarrier” means to transmit or receive data through control and datachannels provided in a cell corresponding to center frequencies andfrequency bands of the downlink and uplink carriers. Although thedescription is directed to an LTE mobile communication system forexplanation convenience, the present invention can be applied to othertypes of wireless communication systems supporting carrier aggregation.Exemplary embodiments of the present invention propose a method andapparatus for determining uplink carrier transmission power per carrierin uplink transmission of the UE.

In the mobile communication system, a UE calculates a requiredtransmission power for single carrier uplink transmission. The uplinktransmission power of the UE is determined by restricting the requiredtransmission power below a predetermined maximum transmission power. Themaximum transmission power is the UE-specific maximum transmission powerdetermined depending on the power class of the UE and is determined inconsideration of at least one of transmission power reduction (ortransmission power backoff) for restricting a cell-specific maximumtransmission power, spurious emission caused by the UE's uplinktransmission below certain levels, a Specific Absorption Rate (SAR, forcontrolling influence of the electromagnetic wave to human body belowpredetermined levels), etc. The required transmission power is thetransmission power calculated based on at least one of a giventransmission resource, a Modulation and Coding Scheme (MCS) level, apath loss, etc., available for the scheduled uplink transmission. Forexample, if uplink transmission is scheduled for a UE at a certain timepoint, the UE calculates required transmission power based on at leastone of the given transmission resource, the MCS level, the path loss,etc.

A first exemplary embodiment of the present invention proposes a methodand apparatus for configuring uplink transmission power of a UE based ona SAR.

First Exemplary Embodiment

A description is made of the method for determining uplink transmissionpower in case where multiple serving cells perform uplink transmissionin consideration of SAR requirements while maintaining compatibilitywith an uplink transmission power determination process of the relatedart that is designed for single serving cell environment. In a case ofmulticarrier uplink transmission, i.e., if a multicarrier uplinkscheduling command for performing uplink transmission in one or morecells (hereinafter, receiving uplink scheduling for a certain cell meansbeing allocated uplink transmission resources and MCS level in thecell), the UE calculates the required transmission power per uplinkusing the same method as the calculation method of the related art. TheUE restricts the required transmission power below a predeterminedmaximum allowed transmission power.

In the first exemplary embodiment of the present invention, the maximumallowed transmission power per serving cell is referred to as a type 1maximum transmission power. The UE compares the sum of the valuesrestricted to the type 1 maximum transmission power with another maximumallowed transmission power. Here, the other maximum allowed transmissionpower is applied to all of the UEs and is referred to as type 2 maximumtransmission power. If the sum of the required transmission powersrestricted to the type 1 maximum transmission power is greater than thetype 2 maximum transmission power, the UE reduces the uplinktransmission powers to be equal to the type 2 maximum transmission poweraccording to a predetermined method. For this purpose, the UE determinesthe type 1 maximum transmission power and type 2 maximum transmissionpower as follows.

The UE determines parameters such as a Maximum Power Reduction (MPR) andAdditive-Maximum Power Reduction (A-MPR) that can be commonly applied toevery cell. The UE applies the same MPR and A-MPR to the cells in whichuplink transmissions are scheduled. In order to configure the type 2maximum transmission power, the UE determines the A-MPR (or P-MPR) as aseparate transmission power reduction parameter for fulfilling a SAR andapplies the determined value. Also, in order to configure the type 2maximum transmission power, the UE uses a value derived from maximumallowed UE transmission powers (P_(EMAX)) and nominal UE power(P_(PowerClass)) in the serving cells in which uplink transmissions arescheduled.

FIG. 4 is a diagram illustrating a principle of determining uplinktransmission power in multicarrier transmission of a UE according to afirst exemplary embodiment of the present invention.

If an uplink scheduling command for uplink transmissions in servingcells 1 and 2 is received, the UE determines its uplink transmissionpower. In the following description, the terms “carrier” and “cell” areused interchangeably. The term “serving cell” denotes the cell in whichdownlink and uplink transmissions or downlink transmission are (is)scheduled for the UE configured with carrier aggregation.

The UE determines the type 1 maximum transmission powers for the servingcells 1 and 2. FIG. 4 is depicted under the assumption that the type 1maximum transmission power 405 of the serving cell 1 (i.e., carrier 1)and the type 1 maximum transmission power 407 of the serving cell 2(i.e., carrier 2) are 200 mW. Here, the type 1 maximum transmissionpowers 405 and 407 can be different from each other. How to determinethe type 1 maximum transmission powers 405 and 407 of the respectiveserving cells are described further below in more detail. In a casewhere the frequency bands of the serving cells 1 and 2 are identicalwith each other, the same MPR and A-MPR are used to determine the type 1maximum transmission power.

For this purpose, the UE calculates the required transmission power ofeach serving cell. In this exemplary embodiment, it is assumed that therequired transmission powers 410 and 415 of serving cells 1 and 2 are150 mW and 250 mW, respectively. Since the required transmission powers410 and 415 are calculated using the same method as the requiredtransmission power determination method, a detailed description thereofis omitted.

The UE compares the required transmission powers 410 and 415 with thetype 1 maximum transmission powers 405 and 407 of the respective servingcells. If the required transmission powers 410 and 415 are greater thanthe type 1 maximum transmission powers 405 and 407 respectively, the UEsets the uplink transmission powers 420 and 425 to type 1 maximumtransmission powers 405 and 407. Otherwise, if the required transmissionpowers 410 and 415 are equal to or less than the type 1 maximumtransmission powers 405 and 407 respectively, the UE sets the uplinktransmission power 420 and 425 to the required transmission power 410and 415. In the following description, the required transmission powerper serving cell which is restricted to the corresponding type 1 maximumtransmission power (i.e., the minimum value between the requiredtransmission power and type 1 maximum transmission power) is referred toas the type 1 transmission power of the serving cell.

In the exemplary case of FIG. 4, the required transmission power 410 of150 mW is less than the type 1 maximum transmission power 405 of 200 mWin the serving cell 1. Accordingly, the UE sets the type 1 uplinktransmission power 420 of the serving cell 1 to the requiredtransmission power 410 of 150 mW.

Meanwhile, the required transmission power 415 of 250 mW is greater thanthe type 1 maximum transmission power 407 of 200 mW. Accordingly, the UEsets the type 1 uplink transmission power 425 of the serving cell 2 tothe type 1 maximum transmission power 407 of 200 mW.

Afterward, the UE determines whether the sum of the type 1 uplinktransmission powers 420 and 425 of the respective serving cells isgreater than the type 2 maximum transmission power 430. The type 2maximum transmission power 430 is configured per UE. The type 2 maximumtransmission power is determined in consideration of at least one ofP-MPR, P_(PowerClass), and P_(EMAX) of the serving cells. If the sum ofthe type 1 uplink transmission powers 420 and 425 is equal to or lessthan the type 2 maximum transmission power 430, the UE sets the uplinktransmission powers 435 and 440 as the type 1 uplink transmission powers420 and 425 of the respective serving cells. Otherwise, if the sum ofthe type 1 uplink transmission powers 420 and 425 is greater than thetype 2 maximum transmission power 430, the UE reduces the sum of thetype 1 uplink transmission powers 420 and 425 so as to match the type 2maximum transmission power 430 according to a predetermined method. Inthe exemplary case of FIG. 4, if the type 2 maximum transmission power430 is 250 mW, the sum of the type 1 uplink transmission powers (350 mW)should be reduced by as much as 100 mW. The UE restricts the sum of thetype 1 uplink transmission powers 420 and 425 to 250 mW using apredetermined method, e.g., reducing the same amount of power. In theexemplary case of FIG. 4, the final uplink transmission power of thecarrier 1 becomes 100 mW while the final uplink transmission power ofthe carrier 2 becomes 150 mW.

A description is made below of the method for determining the type 1maximum transmission power and the type 2 maximum transmission power.

<Type 1 Maximum Transmission Power Determination Method>

The type 1 maximum transmission power of a serving cell c (P_(CMAX,c))is determined according to formula (1). In formula (1), the upper limitof the type 1 maximum transmission power (P_(CMAX) _(—) _(H,c)) isdetermined according to formula (2). The lower limit of type 1 maximumtransmission power (P_(CMAX) _(—) _(L,c)) is determined according toformula (3).P _(CMAX) _(—) _(L,c) ≦P _(CMAX,c) ≦P _(CMAX) _(—) _(H,c)  (1),P _(CMAX) _(—) _(H,c)=MIN{P _(EMAX,c) ,P _(PowerClass)}  (2),P _(CMAX) _(—) _(L,c)=MIN{P _(EMAX,c) −ΔT _(C,c) ,P _(CMAX) _(—) _(H,c)−MPR _(c) −A-MPR _(c) −ΔT _(C,c)}  (3),where P_(EMAX,c), P_(PowerClass), ΔT_(C,c), MPR_(c), and A-MPR_(c) areas follows.

P_(EMAX,c) denotes a maximum allowed UE transmission power in theserving cell c which an eNB notifies the UE of. P_(PowerClass) denotes anominal UE power determined depending on the physical characteristics ofthe UE. The power class of a UE is determined at the manufacturingstate, and the UE reports its power class to the network using apredetermined Radio Resource Control (RRC) message.

ΔT_(C,c), MPR_(c), and A-MPR_(c) are parameters defining a limitationvalue for calculating maximum transmission power in the serving cell cin order to restrict unintended emission or interference to an adjacentchannel to within a certain requirement. In more detail, ΔT_(C,c) is thevalue for allowing additional transmission power adjustment in a casewhere uplink transmission is performed on the edges of a frequency band.For example, if the uplink transmission is performed in a bandwidthcorresponding to the lowest or highest 4 MHz of a certain frequencyband, the UE sets ΔT_(C,c) to 1.5 dB and the rest to 0.

MPR_(c) is the value which is determined based on the amount (i.e.,bandwidth) and modulation scheme of the transmission resources allocatedto the UE. A-MPR_(c) is the value which is determined based on thefrequency band with uplink transmission, local characteristics, anduplink transmission bandwidth. The A-MPR_(c) is used for preparingfrequency bandwidth particularly sensitive to spurious emissionaccording to local characteristics and frequency band characteristics.

In a case where multiple serving cells are involved in uplinktransmission, the aforementioned parameters can be determined per cell.If the cells involved in the uplink transmission are operating on thesame frequency band (the frequency band of a certain cell means theentire frequency resource used for data transmission/reception in thecell) and adjacent to each other (e.g., uplink frequency band of cell 1is x˜x+y MHz and uplink frequency band of cell 2 is x+y˜x+y+z MHz), thesame ΔT_(C,c), MPR_(c), and A-MPR_(c) are commonly applied to theserving cells. In this case, these parameters are determined at a timeeven though multiple cells are involved in the uplink transmission.

ΔT_(C,c), MPR_(c), and A-MPR_(c) are closely associated with thefrequency or frequency band of the cell involved in uplink transmission(e.g., whether the uplink transmission is performed at the edge of agiven frequency bandwidth), or size and position of the frequencyresources for uplink transmission. If n cells are operating oncontiguous frequency bands in the same frequency bandwidth, it can beinterpreted that n cells are equal to a cell having n-fold frequencyband. Accordingly, when the uplink transmission is performed in thecells allocated adjacent frequency bands, it can be modeled that theuplink transmission is performed on the frequency band of one cell whichcorresponds to the frequency bands allocated the multiple cells. Thatis, if the cell 1 (frequency band=x˜x+y MHz) and the cell 2 (frequencyband=x+y˜x+y+z MHz) are involved in the uplink transmission, the UEdetermines ΔT_(C,c), MPR_(c), and A-MPR_(c) under the assumption of avirtual cell (frequency band=x˜x+y+z MHz). Afterward, the UE determinesthe type 1 maximum transmission powers of the cells 1 and 2 usingΔT_(C,c), MPR_(c), and A-MPR_(c).

<Type 2 Maximum Transmission Power Determination Method>

The type 2 maximum transmission power P_(CMAX2) of the UE for uplinktransmission in multiple cells is determined according to formula (4).In formula (4), the upper limit of type 2 maximum transmission powerP_(CMAX2) _(—) _(H) is determined according to formula (5). The lowerlimit of type 2 maximum transmission power P_(CMAX2) _(—) _(L) isdetermined according to formula (6).P _(CMAX2) _(—) _(L) ≦P _(CMAX2) ≦P _(CMAX2) _(—) _(H)  (4),P _(CMAX2) _(—) _(H)=MIN{P _(EMAX2) ,P _(PowerClass)}  (5),P _(CMAX2) _(—) _(L)=MIN{P _(CMAX2) _(—) _(H) −P-MPR,Highest P _(CMAX)_(—) _(L,c)}  (6)

P_(EMAX) is the parameter denoting maximum allowed UE transmission powersignaled per cell. Since P_(EMAX2) is of the simultaneous uplinktransmissions of multiple cells, it is not clear which P_(EMAX,c) shouldbe used as P_(EMAX2). Accordingly, P_(EMAX,c) is set to the valueselected in consideration of P_(EMAX,c) of the cells involved in theuplink transmission. For example, the highest one among the P_(EMAX,c)of the cells involved in the uplink transmission can be selected asP_(EMAX2). Of course another method can be used for determiningP_(EMAX,c). Here, P_(EMAX2) _(—) _(H) can be defined as the valuederived from the P_(PowerClass) and P_(EMAX,c)'s of all of the cellsinvolved in the uplink transmission. For example, the highest one amongthe P_(EMAX,c)'s of all of the cells can be selected as P_(EMAX2) _(—)_(H).

P-MPR is the transmission power reduction value applied for fulfilling aSAR requirement and is determined in consideration of the distancebetween the device and the human body. If the distance between thedevice and the human body becomes close, then P-MPR is set to arelatively high value since the total transmission power should bedecreased. In contrast, if the distance between the device and the humanbody become far, P-MPR is set to a relatively low value since the totaltransmission power should be increased.

P-MPR is the parameter for controlling a total amount of electromagneticenergy being radiated from a device. Accordingly, it is preferred to useP-MPR as the parameter for adjusting P_(CMAX2) restricting the entireuplink transmission power of the device rather than as the parameter foradjusting P_(CMAX,c) for restricting the per-cell transmission power ofthe device. If P_(CMAX,c) is adjusted with P-MPR, it may incur a sideeffect from using an unnecessarily high P-MPR.

Assuming P_(CMAX,c) of 100 mW for cell 1 and P_(CMAX,c) of 200 mW forcell 2 without consideration of P-MPR, P_(CMAX2) of 200 mW for uplinktransmission of UE in the cells 1 and 2, and final transmission power of150 mW for satisfying the SAR, the P-MPR should be set to 50 mW for cell1 and 100 mW for cell 2 in order to match the final transmission powerof 150 mW by applying the P-MPR to P_(CMAX,c). However, the finaltransmission power obtained using these values may not have aninappropriate value. That is, if the required transmission powers forboth the cells 1 and 2 are 100 mW, the final transmission powers for thecells 1 and 2 that are obtained by applying the P-MPR separately become50 mW and 100 mW respectively. This means that the transmission powerreduction occurs only for the cell 1. In contrast, if the P-MPR isapplied to P_(CMAX2), the sum of the type 1 transmission power of 100 mWfor cell 1 and the type 1 transmission power of 100 mW for cell 2 islimited to P_(CMAX2) adjusted by P-MPR, i.e., 150 mW. Accordingly, thetransmission power reduction is applied for the cells 1 and 2, resultingin final transmission power of 75 mW for both the cells 1 and 2. Thismeans that it is preferred to apply P-MPR to P_(CMAX2) for configuringtransmission power of the UE.

As described above, the UE determines P_(CMAX2) by applying at least oneof P_(EMAX)'s for the cells involved in uplink transmission,P_(PowerClass), P-MPR, ΔT_(C,c), MPR_(c), and A-MPR_(c).

FIG. 5 is a signaling diagram illustrating a method for determininguplink transmission power of a UE according to the first exemplaryembodiment of the present invention. The mobile communication systemdepicted in FIG. 5 includes a UE 505 supporting multicarrier uplinktransmission and an eNB 510 supporting carrier aggregation.

Referring to FIG. 5, the UE 505 sends the eNB 510 a message such as UEcapability report message carrying the information on type 1 maximumtransmission power and type 2 maximum transmission power in step 515.The information on the type 2 maximum transmission power is theinformation provided for the eNB 510 to check the type 2 maximumtransmission power of the UE 505. The information on the type 2 maximumtransmission power can be the information directly indicating the type 2maximum transmission power or the information on the Power Class of theUE 505.

The eNB 510 sends the UE 505 information on the maxim allowedtransmission power P_(EMAX,c) per serving cell, i.e., carrier, in step520. P_(EMAX,c) is the parameter indicating the maximum allowed UEoutput power for cell c in consideration of inter-cell interference.P_(EMAX,c) can be transmitted to the UE 505 in system information or ina predetermined control message for the redundant serving cellsconfigured for the UE 505. In more detail, when the UE has only oneserving cell before aggregating carriers, the P_(EMAX,c) for thecorresponding cell can be acquired in the system information of thecorresponding cell. However, P_(EMAX,c) for the serving cells of whichcarriers are newly aggregated can be informed through a peer to peercontrol message, i.e., a RRC CONNECTION RECONFIGURATION message,transmitted from the eNB to the UE.

The UE 505 determines the type 1 maximum transmission power per carrierusing P_(EMAX,c) and P_(PowerClass) provided by the eNB 510 in step 525.The upper limit of the type 1 maximum transmission power is determinedaccording to formula (2). Afterward, the UE receives an uplinkscheduling command instructing uplink transmission in multiple servingcells from the eNB 510 in step 530. For example, the UE 515 receives theuplink grant (CELL 1, t1) instructing the uplink transmission in cell 1of carrier 1 at time t1 and the uplink grant (CELL 1, t2) instructingthe uplink transmission in cell 2 of carrier 2 at time t2.

The UE 505 determines the lower limits of the type 1 maximumtransmission powers for the carriers on which transmission is scheduledand type 2 maximum transmission power in step 535. In more detail, ifthe frequency bands of the cells involved in the uplink transmission areadjacent with each other in a given frequency bandwidth, the UEdetermines a set of ΔT_(C,c), MPR_(c), and A-MPR_(c) in consideration ofthe conditions of the two cells. Next, the UE determines the lower limitof the type 1 maximum transmission power for the serving cells usingformula (3). The UE 505 also determines the type 2 maximum transmissionpower according to formulas (4) to (6).

Next, the UE 505 determines the type 1 maximum transmission powers forcarriers and type 2 maximum transmission power in step 540. Finally, theUE determines the final transmission power per carrier in step 545. Inmore detail, the UE 505 determines the uplink transmission power perserving cell using the selected type 1 maximum transmission power andtype 2 maximum transmission power. The UE 505 calculates the requiredtransmission power per serving cell. Next, the UE 505 limits therequired transmission power to the type 1 maximum transmission power forthe corresponding serving cell so as to determine the type 1 uplinktransmission power per serving cell. The UE 505 calculates the sum ofthe per-cell type 1 uplink transmission powers and compares the sum ofthe per-cell type 1 uplink transmission powers with the type 2 maximumtransmission power. If the sum of the per-cell type 1 uplinktransmission powers is equal to or less than the type 2 maximumtransmission power, the UE determines the per-cell type 1 uplinktransmission powers as the uplink transmission powers of the servingcells. If a sum of the per-cell type 1 uplink transmission powers isgreater than the type 2 maximum transmission power, the UE performstransmission power reduction on the per-cell type 1 uplink transmissionpowers to limit the sum of the per-cell type 1 uplink transmissionpowers to the type 2 maximum transmission power.

FIG. 6 is a flowchart illustrating a method for determining uplinktransmission power of a UE according to the first exemplary embodimentof the present invention.

Referring to FIG. 6, the UE receives a command for multicarrier uplinktransmission in step 605. Upon receipt of the multicarrier uplinktransmission command, the UE determines uplink transmission power instep 610.

At step 610, the UE calculates required transmission power per uplinkcarrier. Next, the UE determines type 1 transmission powers based onper-carrier type 1 maximum transmission powers and per-carrier requiredtransmission powers in step 615. That is, the UE determines the minimumvalue between the type 1 maximum transmission power and the requiredtransmission power for the corresponding carrier as the type 1 uplinktransmission power for the corresponding carrier. Here, the UE can applythe same ΔT_(C,c), MPR_(c), and A-MPR_(c) to determine the type 1maximum transmission powers for respective serving cells.

The UE adds up the type 1 uplink transmission powers in step 620. Next,the UE determines whether the sum of the type 1 uplink transmissionpowers is greater than the type 2 maximum transmission power in step625. Here, the type 2 maximum transmission power is determined based onthe following parameters:

-   -   P_(EMAX)'s for cells involved in uplink transmission;    -   P_(PowerClass) of UE;    -   P-MPR at corresponding time point; and    -   ΔT_(C,c), MPR_(c), and A-MPR_(c) used for determining type 1        maximum transmission powers.

If the sum of the type 1 uplink transmission powers is greater than thetype 2 maximum transmission power at step 625, the UE reduces the type 1uplink transmission powers such that the sum of the type 1 uplinktransmission powers is equal to the type 2 maximum transmission power instep 630. For example, the UE divides a difference between the sum ofthe type 1 uplink transmission powers and the type 2 maximumtransmission power by a number of type 1 uplink transmission powers andsubtracts the resulting value from the respective type 1 uplinktransmission powers. Next, the UE determines the reduced type 1 uplinktransmission powers as the final uplink transmission powers for therespective carriers in step 635.

If the sum of the type 1 uplink transmission powers is equal to or lessthan the type 2 maximum transmission power at step 625, the UEdetermines the type 1 uplink transmission powers as the final uplinktransmission powers for the respective carriers in step 640.

FIG. 7 is a block diagram illustrating a configuration of a UE accordingto the first exemplary embodiment of the present invention.

Referring to FIG. 7, the UE according to an exemplary embodiment of thepresent invention includes a transceiver 705, a controller 710, amultiplexer/demultiplexer 720, higher layer devices 725 and 730, and acontrol message processor 735.

The transceiver 705 receives data and control signals on downlinkchannels of the serving cell and transmits data and control signals onuplink channels of the serving cell. In a case where multiple servingcells are configured, the transceiver 705 performs data and controlsignal transmission/reception in the multiple serving cells.

The controller 710 checks scheduling commands, e.g., uplink grants,received by the transceiver 705 and controls the transceiver 705 and themultiplexer/demultiplexer 720 to perform uplink transmission with anappropriate transmission resource at an appropriate time. That is, thecontroller 710 determines type 1 maximum transmission power per carrierfor uplink transmission according to formulas (1) to (3).

The controller 710 also determines the type 2 maximum transmission poweraccording to formulas (4) to (6). Next, the controller 710 determinesthe type 1 uplink transmission power by comparing the requiredtransmission power with the determined type 1 maximum transmission powerper cell as shown in step 615 of FIG. 6. The controller 710 alsodetermines the final uplink transmission power per serving cell bycomparing the sum of the type 1 uplink transmission powers forindividual serving cells with the determined type 2 maximum transmissionpower. The controller 710 also controls the transceiver 705 to performuplink transmission with the final uplink transmission power determinedper carrier.

The multiplexer/demultiplexer 720 can multiplex the data generated bythe higher layer devices 725 and/or control message processor 735. Themultiplexer/demultiplexer 720 also can demultiplex the received data tobe transferred to the higher layer devices 725 and 730 and/or thecontrol message processing unit 735.

Each of the higher layer devices 725 and 730 is configured per service.The higher layer devices 725 and 730 process the data generated by auser service such as File Transfer Protocol (FTP) or VoIP and deliverthe process result to the multiplexer/demultiplexer 720 or process thedata from the multiplexer/demultiplexer 720 and delivers the processresult to the service applications of a higher layer.

The control message processor 735 processes the control message receivedfrom the eNB and takes an appropriate action. That is, the controlmessage processor 735 extracts the uplink transmission powerconfiguration information per serving cell, e.g., P_(EMAX,c) per servingcell, from the control message and delivers the extracted information tothe controller 710.

Second Exemplary Embodiment

The displacement of P_(CMAX2) is important information referenced by theeNB for uplink scheduling. The second exemplary embodiment of thepresent invention proposes a method for reporting the displacement ofP_(CMAX2) when the displacement of P_(CMAX2) of the UE becomes greaterthan a predetermined value.

The second exemplary embodiment of the present invention may use thePower Headroom Report (PHR) MAC Control Element (CE) of the related artrather than introducing a new control message for reporting P_(CMAX2).

The PHR MAC CE is the control message for the UE to notify the eNB ofthe Power Headroom (PH) of the UE. Here, PH is the difference betweenP_(CMAX) and required transmission power. One PHR includes PHs ofmultiple serving cells. PHR is triggered when a predetermined conditionis fulfilled and multiplexed in a MAC PDU in the first uplinktransmission.

In the present exemplary embodiment, the PHR trigger condition includesthe condition where the displacement of P_(CMAX2) becomes equal to orgreater than a predetermined value.

FIG. 8 is a diagram illustrating a structure of a PHR for use in anuplink transmission power configuration method according to an exemplaryembodiment of the present invention.

Referring to FIG. 8, PHR is composed of a 1-byte bitmap 805 and aplurality of PHs 810 and 820 paired with P_(CMAX,c) 815 and 825. Thebitmap 805 indicates the serving cells for which PH is included. The PHRincludes PHs for the serving cells activated at the time when the PHR istriggered, and P_(CMAX,c) is included selectively. If there is only oneserving cell in an active state or no redundant uplink carrier isconfigured, the PHR is formed as a combination of a bitmap and aPH/P_(CMAX,c).

In a case where there is only one serving cell in active state,P_(CMAX2) is reported in the P_(CMAX,c) field of the related art. In acase where there is more than one active cell, a new field is introducedto report P_(CMAX2). That is, P_(CMAX2) is reported in the P_(CMAX,c)field when there is only one active cell since P_(CMAX,c) and P_(CMAX2)are equal to each other and in a separate field when there is more thanone active cell since the P_(CMAX,c) and P_(CMAX2) are different fromeach other.

In a case where there is more than one active cell, the eNB notifies theUE of the existence of the P_(CMAX2) field using a predetermined bit ofthe bitmap. The predetermined bit can be the last bit of the bitmap.

FIG. 9 is a diagram illustrating a structure of PHR for use in an uplinktransmission power configuration method according to a second exemplaryembodiment of the present invention.

FIG. 9 shows a PHR format 905 for use in the case where only one activecell exists and another PHR format 910 for used in the case where morethan one active cell exists. That is, the first PHR format 905 includesa P_(CMAX2) field containing P_(CMAX2) for the active cell. The secondPHR format 910 is used when PHR is triggered according to the change ofP_(CMAX2).

In a PHR function configuration state, the eNB can configure a P_(CMAX2)report in order for the UE to report P_(CMAX2) or not. That is, the eNBsends the UE a one-bit information indicating whether P_(CMAX2) is to bereported. If the P_(CMAX2) report is configured positively, the UE sendsa PHR containing P_(CMAX2).

FIG. 10 is a flowchart illustrating a method for transmitting a PHRaccording to the second exemplary embodiment of the present invention.

Referring to FIG. 10, the displacement of P_(CMAX2) becomes greater thana predetermined value so as to trigger PHR in step 1005\. PHR istriggered when the path loss of a reference cell (i.e., path lossreference cell) changes more than a predetermined amount among theactive cells or a predetermined time duration elapses after transmissionof the PHR. If the path loss in a certain serving cell A is referencedfor another serving cell B, this means that the pass loss of the servingcell A is referenced for determining the uplink transmission power inthe serving cell B. Accordingly, when the serving cells A and B areidentical with each other, the uplink transmission power can bedetermined using the path loss of the downlink channel of each cell.When the serving cells A and B are different from each other, the uplinktransmission power can be determined using the path loss on respectivedownlink channels. In this case, the eNB informs the UE of the path lossreference cell through RRC signaling. The UE calculates P_(CMAX2) usingformulas (4), (5), and (6) and, if the P_(CMAX2) has changed by morethan a predetermined amount as compared to the most recently receivedvalue, the PHR is triggered.

The UE calculates PH per serving cell according to a predeterminedmethod in consideration of the existence of uplink transmission in step1010. That is, the UE calculates PHs of the cells currently in an activestate. At this time, the UE calculates PH in a different manneraccording to whether a certain serving cell has real uplinktransmission. The UE uses <PH calculation method 1> for the serving cellhaving real uplink transmission and <PH calculation method 2> for theserving cell having no real uplink transmission. <PH calculation method1> is defined as follows.

<PH Calculation Method 1>PH=Real P _(CMAX,c)−Real PUSCH power

The real P_(CMAX,c) is the maximum transmission power of the servingcell c which is determined by formulas (1), (2), and (3) in a situationwhere a real MAC PDU is transmitted. Formula (3) can be modified toformula (7) in consideration of P-MPR_(c).P _(CMAX2) _(—) _(L,c)=MIN{P _(EMAX,c) −P- MPR _(c) −T _(C,c) P _(CMAX2)_(—) _(H,c) −MPR _(c) −A-MPR _(c) −T _(C,c)}  (7)

The real PUSCH power is the transmission power required for transmittingMAC PDU while guaranteeing a predetermined transmission quality. ThePUSCH power of an i^(th) subframe in the serving cell c is calculatedusing formula (8) with the number of resource block M_(PUSCH,c) (i),power offset induced from MCS Δ_(TF,c), path loss PL_(c), and TPCcommand accumulation value f_(c)(i).PUSCH power(i)={10 log₁₀(M _(PUSCH,c)(i))+P _(O) _(—)_(PUCCH,c)(j)+α_(c)(j)·PL _(c)+Δ_(TF,c)(i)+f _(c)(i)}  (8)

In formula (8), PL_(c) denotes the path loss in the cell configured toprovide the service cell c with the path loss. That is, the path lossused for determining uplink transmission power in a certain serving cellis the path loss of the downlink channel of the corresponding cell orthe path loss of the downlink channel of a different cell. The path lossto be used is notified by the eNB to the UE in the call setup process.

In formula (8), f_(c)(i) denotes the accumulation value of TransmissionPower Control (TPC) in serving cell c. P_(O) _(—) _(PUCCH,c) denotes ahigher layer parameter composed of cell-specific and UE-specific values.α_(c) denotes the weight applied to the path loss when the uplinktransmission power is calculated using the 3-bit cell-specific valueprovided from higher layers. As α_(c) increases, the influence of thepath loss to the uplink transmission power increases.

<PH Calculation Method 2>PH=Reference P _(CMAX,c)−Reference PUSCH power

The Reference P_(CMAX,c) denotes the maximum transmission power in thecell having no real uplink transmission. Since no real uplinktransmission occurs, the maximum transmission power has no real meaningbut is used to calculate PH. The Reference P_(CMAX,c) is the valueobtained using formulas (1), (2), and (7) when P-MPR_(c), T_(C,c), andA-MPR_(c) are all set to 0. The reason why the parameters are set to 0is to notify the eNB of the value of Reference P_(CMAX,c) without aseparate report for P_(CMAX,c). In other words, if one of the parametersis set to a non-zero value, the eNB cannot be aware of the P_(CMAX,c)used in the PH calculation such that it is necessary to reportP_(CMAX,c) separately. However, it is difficult to acquire an accurateP_(CMAX,c) from PH for the serving cell having no real uplinktransmission. Accordingly, the parameters for the serving cell having noreal uplink transmission are set to 0 in order to negate the report ofinaccurate information, resulting in removal of inefficiency.

The Reference PUSCH power is calculated by applying formula (8) underthe assumption of scheduling of 1 transmission resource block with thelowest MCS. That is, M_(PUSCH,c)(i) as Reference PUSCH power is set to1, and Δ_(TF,c) is set to the lowest value of 0 as shown in formula (9).PUSCH power(i)={P _(O) _(—) _(PUSCH,c)(j)+α_(c)(j)·PL _(c) +f_(c)(i)}  (9)

The UE calculates PHs of the serving cells currently in an active stateusing <PH calculation method 1> and <PH calculation method 2>, and theprocedure proceeds to step 1015.

The UE determines whether a number of currently active uplink servingcells is greater than 1 in step 1015. The uplink serving cell means theserving cell configured for uplink transmission. If the number ofcurrently active uplink serving cells is 1, the procedure goes to step1020 and, otherwise, if the number of currently active uplink servingcells is greater than 1, goes to step 1025.

At step 1020, the UE generates PHR in the format as denoted by referencenumber 905 of FIG. 9. The PHR includes PHs of the serving cells in anactive state, and the P_(CMAX,c) field contains P_(CMAX2). Since theP_(CMAX2) and the P_(CMAX,c) are identical with each other when only oneactive uplink serving cell exists, it is not necessary for the UE toreport the P_(CMAX2) separately. Accordingly, when there is only oneactive uplink serving cell, the UE does not report P_(CMAX2).

At step 1025, the UE generates PHR in the format as denoted by referencenumber 910 of FIG. 9. That is, the UE configures the first byte of thePHR to indicate the PHs included in the corresponding PHR. The last bitof the first byte is used for indicating whether P_(CMAX2) filed exists.If PHR is triggered due to the change of P_(CMAX2), the UE insertsP_(CMAX2) in PHR and sets the last bit of the first byte to 1. Next, theUE inserts the PHs of the uplink serving cells in an active state. In acase where PH is calculated using the PH calculation method 1 (i.e.,using real P_(CMAX,c) and real PUSCH power, or if there is real uplinktransmission in the corresponding serving cell), the UE reportsP_(CMAX,c) too. Otherwise, if PH is calculated using the PH calculationmethod 2 (i.e., using reference P_(CMAX,c) and reference PUSCH power, orif there is no real uplink transmission in the corresponding servingcell), the UE does not report P_(CMAX,c).

The UE inserts P_(CMAX2) in the last byte. The UE can insert the valueobtained by subtracting the sum of the uplink transmission powers foruse in the active uplink serving cells from P_(CMAX2) rather thanP_(CMAX2) itself.

Finally, the UE encapsulates the generated PHR in a MAC PDU andtransmits the MAC PDU to the eNB in step 1030.

The UE according to the second exemplary embodiment of the presentinvention is identical with that of the first exemplary embodimentexcept for the operations the multiplexer/demultiplexer.

In the second exemplary embodiment, the controller determines whetherPHR is triggered, calculates PHs for active serving cells, P_(CMAX,c),and P_(CMAX2), generates PHR, and delivers the PHR to themultiplexer/demultiplexer. The multiplexer/demultiplexer according tothe second exemplary embodiment multiplexes the PHR from the controllerinto a MAC PDU and transfers the MAC PDU to the transceiver.

As described above, the uplink transmission power configuration methodand apparatus of exemplary embodiments of the present invention iscapable of determining the uplink transmission power efficiently whileminimizing the inter-frequency band or inter-cell interference andmaintaining the required transmission powers for aggregated uplinkcarriers as much as possible in the mobile communication systemsupporting carrier aggregation.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the presentinvention as defined by the appended claims and their equivalents.

What is claimed is:
 1. A method for determining uplink transmission power of a user equipment (UE) supporting carrier aggregation, the method comprising: receiving uplink scheduling information for performing uplink transmission in at least two serving cells from a base station; determining a first uplink maximum transmission power of each of the at least two serving cells; determining a second uplink maximum transmission power of the UE; and determining an uplink transmission power of each of the at least two serving cells based on the first uplink maximum transmission power of each of the at least two serving cells and the second uplink maximum transmission power of the UE, wherein a lower limit of the second uplink maximum transmission power is determined based on a maximum power reduction (MPR) parameter, an additive-maximum power reduction (A-MPR) parameter and a p-maximum power reduction (P-MPR).
 2. The method of claim 1, wherein an upper limit of the second uplink maximum transmission power is determined based on information on maximum allowed transmission power of each of the at least two serving cells involved in the uplink transmission of the UE and information related to power class of the UE.
 3. The method of claim 1, wherein the determining of the first uplink maximum transmission power of each of the at least two serving cells comprises applying a maximum power reduction (MPR) parameter and an additive-maximum power reduction (A-MPR) parameter commonly to serving cells involved in the uplink transmission of the UE.
 4. The method of claim 3, wherein the MPR parameter and the A-MPR parameter are commonly applied to each of the at least two serving cells, when the cells involved in the uplink transmission of the UE are operating on the same frequency band and adjacent to each other.
 5. The method of claim 1, wherein the determining of the first uplink maximum transmission power of each of the at least two serving cells and the determining of the second uplink maximum transmission power of the UE comprises applying an identical MPR and an identical A-MPR commonly.
 6. The method of claim 1, wherein the determining of the first uplink maximum transmission power of each of the at least two serving cells comprises comparing the first uplink maximum transmission power of each of the at least two serving cells and a required transmission power of each of the at least two serving cells.
 7. The method of claim 1, further comprising: receiving information related to maximum allowed transmission power of each of the at least two serving cells for determining the first uplink maximum transmission power of each of the at least two serving cells, wherein the information related to serving cell before carrier aggregation is acquired via a SYSTEM INFORMATION message, the information related to serving cells after a carrier aggregation is acquired via a RRC CONNECTION RECONFIGURATION message.
 8. The method of claim 1, wherein the determining of the uplink transmission power of each of the at least two serving cells comprises: when a sum of the first uplink maximum transmission power of each of the at least two serving cells is greater than a per-UE maximum output power, reducing the first uplink transmission maximum power to make the sum of the first uplink maximum transmission power of each of the at least two serving cells equal to the second uplink maximum transmission power; and determining the reduced first uplink maximum transmission power of each of the at least two serving cells as the uplink transmission power of each of the at least two serving cells.
 9. The method of claim 1, wherein the determining of the uplink transmission power of each of the at least two serving cells comprises, when a sum of the first uplink maximum transmission power of each of the at least two serving cells is equal to or less than the second uplink maximum transmission power, determining the first uplink maximum transmission power of each of the at least two serving cells as the uplink transmission power of each of the at least two serving cells.
 10. An apparatus for determining uplink transmission power of a user equipment (UE) supporting carrier aggregation, the apparatus comprising: a transceiver configured to transmit and receive data in multiple serving cells; and a controller configured to receive uplink scheduling information for performing uplink transmission in at least two serving cell from a base station, to control to determine a first uplink maximum transmission power of each of the at least two serving cells, to determine a second uplink maximum transmission power of the UE, and to determine a uplink transmission power of each of the at least two serving cells based on the first uplink maximum transmission power of each of the at least two serving cells and the second uplink maximum transmission power of the UE, wherein a lower limit of the second uplink maximum transmission power is determined based on a Maximum Power Reduction (MPR) parameter, an Additive-Maximum Power Reduction (A-MPR) parameter and a P-Maximum Power Reduction (P-MPR).
 11. The apparatus of claim 10, wherein an upper limit of the second uplink maximum transmission power is determined based on information on maximum allowed transmission power of each of the at least two serving cells involved in the uplink transmission of the UE and information related to a power class of the UE.
 12. The apparatus of claim 10, wherein the controller is further configured to apply a maximum power reduction (MPR) parameter and an additive-maximum power reduction (A-MPR) parameter commonly to serving cells involved in the uplink transmission of the UE, when the UE determines the first uplink maximum transmission power of each of the at least two serving cells.
 13. The apparatus of claim 12, wherein the MPR parameter and the A-MPR parameter are commonly applied to each of the at least serving cells, when the cells involved in the uplink transmission of the UE are operating on the same frequency band and adjacent to each other.
 14. The apparatus of claim 10, wherein the controller is further configured to apply an identical MPR and an identical A-MPR commonly, when the UE determines the first uplink maximum transmission power of each of the at least two serving cells and the second uplink maximum transmission power of the UE.
 15. The apparatus of claim 10, wherein the controller is further configured to compare the first uplink maximum transmission power of each of the at least two serving cells and a required transmission power of each of the at least two serving cells.
 16. The apparatus of claim 10, wherein the controller is further configured to control to receive information related to a maximum allowed transmission power of each of the at least two serving cells for determining the first uplink maximum transmission power of each of the at least two serving cells, wherein the information related to serving cell before carrier aggregation is acquired via a SYSTEM INFORMATION message, the information related to serving cells after a carrier aggregation is acquired via a RRC CONNECTION RECONFIGURATION message.
 17. The apparatus of claim 10, wherein the controller is further configured to control, when the UE determines an uplink transmission power of each of the at least two serving cells and when a sum of the first uplink maximum transmission power of each of the at least two serving cells is greater than a per-UE maximum output power, to reduce the first uplink transmission maximum power to make the sum of the first uplink maximum transmission power of each of the at least two serving cells equal to the second uplink maximum transmission power, and to determine the reduced first uplink maximum transmission power of each of the at least two serving cells as the uplink transmission power of each of the at least two serving cells.
 18. The apparatus of claim 10, wherein the controller is further configured to control, when the UE determines a uplink transmission power of each of the at least two serving cells and when a sum of the first uplink maximum transmission power of each of the at least two serving cells is equal to or less than the second uplink maximum transmission power, to determine the first uplink maximum transmission power of each of the at least two serving cells as the uplink transmission power of each of the at least two serving cells. 